1. Field of the Invention
This invention relates to an image pickup optical system and an optical apparatus using this optical system, and in particular, to a decentering optical system imparting power to a reflecting surface and an optical apparatus using this optical system. The optical apparatus refers, for example, to a video camera, a digital still camera, a film scanner, an endoscope, or a mobile phone.
2. Description of Related Art
Recently, in image-forming optical systems used in video cameras, digital cameras, film scanners, or endoscopes, compact, lightweight, and low-cost designs according to compactness of image sensors have been required in the optical systems themselves. In addition, with the advent in recent years of products incorporating electronic image pickup optical systems in mobile phones, PDAs, and notebook PCs, the need for further slim designs of the optical systems has been emphasized.
As a conventional optical system constructed for the purpose of the compact design, a prism optical system using a free-formed surface is proposed.
An optical system constructed for the purpose of the slim design is proposed.
In these optical systems, optical members constituting the optical systems for slim and compact designs are decentered. In each of the optical systems, the power of an optical member located on the object side of the pupil of the optical system varies with X and Y directions in a plane perpendicular to the optical axis, and the pupil located at the position of an aperture stop has an elliptical shape.